Francoise Delpech

Towards the modelling and control of NOx emission in a fluidized bed sludge combustor

Sludge incineration is a widely used technology because of its large volume reduction and complete organic destruction. However, incineration does encounter a number of drawbacks, among which are notably carbon monoxide (CO) and nitrogen oxides (NOx) emissions. Carbon monoxide emissions are efficiently avoided by oxygen regulation in the furnace. Nitrogen oxide (NOx) formation, however, is very complex and not well known. This paper proposes a dynamic model of sludge combustion in an industrial fluidized bed combustor mainly focused on NOx formation. The model is tuned with industrial data. A control strategy is proposed to improve on the current industrial regulation, simultaneously ensuring CO and NOx control, yet without decreasing the combustion efficiency. The results are sufficiently acceptable for this process to be carried out in a real incinerator plant.

The range distributions of some Ungulate Mammals during the Dryas I (Recent Würm) in Aquitaine. Paleoecological implications

Abstract This paper concerns certain ungulate species represented in 19 archaeological sites from the Aquitaine region of southwestern France; twelve of these sites have radiocarbon dates of from 15500 to 13500 BP. Species of concern include: Cervus elaphus L., Rangifer tarandus L., Bison priscus Boj. , Saiga tatarica L., Capra ibex or (and) Capra pyrenaica Schinz , Rupicapra rupicapra L. and Equus caballus L. Palynological and sedimentological analyses carried out conjointly with faunal studies provide data on late Pleistocene climates in the region. These indicate that the observed associations among ungulate species occurred under the widespread cold and dry conditions of the Dryas I phase, the last period when typical Wurmian steppic vegetation was present over most of the Aquitaine. Examination of ungulate spatial distributions provides evidence for each species environmental requirements. Ecological tolerances are especially narrow for the Saiga Antelope and for the Bouquetin.

SFGP 2007 - An Adsorption and Photocatalysis Study of Ethyl Hexanoate

Titanium dioxide photocatalysis is an emerging and very promising technology to reduce odorous industrial pollution. Using an adsorbent could offer an interesting way to enhance the pollutants photodecomposition rate. Our project deals with industrial emissions that contain a high concentration of esters such as ethyl hexanoate (EH) which has a very low olfactory detection threshold and it is very unpleasant both in industrial indoor air and in outer emission.Photocatalysis is performed here within a mixed flow reactor involving two fibrous media. The first one is a media coated with TiO2, SiO2 and zeolite and the second one is a mixture of TiO2, SiO2 and activated carbon (AC). A three-level full factorial design of experiments is performed with TiO2 x96 zeolite media. It permits us to determine the impact of two main parameters on adsorption and photocatalysis phenomena; moisture inflow (from 0 to 15 g.m-3) and pollutant concentration (from 50 to 150 mg/m3). Adsorption capacity ranges between 4 to 37 mg EH/g of media. It decreases while humidity increases due to competitive adsorption of water and pollutants on photocatalyst sites. Moreover the EH conversion rate increases when inlet concentration decreases. An optimal relative humidity can be deduced to reach an optimal conversion rate for a fixed inlet concentration. Conversion rate values of 24, 39 and 25 % are observed at respective humidity values of 0, 7.5 and 15 g.m-3 for a 100 mg/m-3 inlet concentration. The designs of the experiment are descriptive and predictive for adsorption capacity and degradation rates.With TiO2 x96 AC media, experiments are carried out at 15 g.m-3 of humidity and 100 mg/m3 of EH inlet concentration. As expected, a high-grade adsorbent media leads to a higher adsorption capacity compared with TiO2 x96 zeolite media (130 instead of 4 mg EH/g of media). Nevertheless, even if adsorption capacity is higher, conversion rate decreases (23 % instead of 46 %). Thus, in our experimental conditions, a very high content of adsorbent in the photocatalyst media does not improve the global degradation efficiency probably due to the lack of desorption of pollutants from AC.

Dynamic model of NOx emission for a fluidized bed sludge combustor

Abstract Abstract Sludge incineration in fluidized bed is a very complex process, producing gaseous pollutants (carbon monoxide (CO) and nitrogen oxides (NOx)). The legislative norms need to be respected in spite of variations of sludge in composition and in quantity. The NOx formation, due to lots of chemical reactions from sludge nitrogen, is partly unknown. This paper deals with the design of a dynamic model of NOx emissions for a fluidized bed sludge combustor to be used in control strategy. The model is validated with industrial data, and the simulation results validate the simplification hypotheses, but need the reconstruction of sludge composition.